Bypass mass spectroscopy and gas chromatography with an Arduino controller and MQ gas detector.

The most accurate method of detection of gases and environmental pollutants is considered to be a gas chromatograph-mass spectrometer (GC-MS), which analyzes unknown substances by the light emitted from them.   This Wikipedia article provides a comprehensive introduction to this type of analytical device.  According to Wikipedia, the GC-MS  came under development as a forensic tool in the 1950s.  Some of the uses to which its capabilities have been put include the following:

Food, beverage and perfume analysis

Foods and beverages contain numerous aromatic compounds, some naturally present in the raw materials and some forming during processing. GC-MS is extensively used for the analysis of these compounds which include esters, fatty acids, alcohols, aldehydes, terpenes etc. It is also used to detect and measure contaminants from spoilage or adulteration which may be harmful and which is often controlled by governmental agencies, for example pesticides.

Astrochemistry

Several GC-MS have left earth. Two were brought to Mars by the Viking program.^[21]Venera 11 and 12 and Pioneer Venus analysed the atmosphere of Venus with GC-MS.^[22] The Huygens probe of the Cassini-Huygens mission landed one GC-MS on Saturn’s largest moon, Titan.^[23] The material in the comet67P/Churyumov-Gerasimenko will be analysed by the Rosetta mission with a chiral GC-MS in 2014.^[24]

Medicine

Dozens of congenital metabolic diseases also known as Inborn error of metabolism are now detectable by newborn screening tests, especially the testing using gas chromatography–mass spectrometry. GC-MS can determine compounds in urine even in minor concentration. These compounds are normally not present but appear in individuals suffering with metabolic disorders. This is increasingly becoming a common way to diagnose IEM for earlier diagnosis and institution of treatment eventually leading to a better outcome. It is now possible to test a newborn for over 100 genetic metabolic disorders by a urine test at birth based on GC-MS.

While GC-MS technology is generally so expensive it cannot always be employed where needed, publiclab.org has a plan to enable every citizen scientist to detect pollution in the home and in the environment.  The basis and method employed in the publiclab.org project has been summarized as follows:

A spec[trometer] identifies the specific mix of colors that is absorbed by a sample producing what is known as an ‘absorption spectra‘ which is characteristic of that sample. Think of it like a fingerprint for every material. To do this accurately, the spec needs something that can effectively split light into its constituent colors. One option is to use a prism, which you’ve probably seen at some point. Another way is to use a ‘diffraction grating’ which is a surface with many small parallel lines that can also do the same job of splitting light.
DVD as a diffraction grating

DVD as a diffraction grating for a spectrometer

One cool everyday object that acts as a diffraction grating is a CD or DVD. The tiny grooves on the disc act like a grating and split white light giving off the rainbow of colors that you see on its back side. The Public Lab DIY spec uses a DVD as a diffraction grating. The image below describes how a simple DIY spec works. And that’s the Cliffs Notes version. Public Lab’s spectrometer curriculum has lots more detail!

The Public Lab DIY Spectrometer

Our friends over at Public Lab have made it possible for you to do your own spectrometric analysis at home! When it started, the goal of the project was to create a cheap, do-it-yourself spectrometer that anybody could use to analyze materials and contaminants like oil spills and tar residues in urban waterways. In 2012, the team came up with an idea for a spec and crowd-funded it on Kickstarter.  The Kickstarter project was a massive success and now Public Lab is selling the DIY desktop kit for $40 in its online store. However, if you prefer to build it from the materials you have at home, they have a great instruction manual for how to make it yourself.

They have also made a smartphone compatible Foldable Mini Spectrometer ($10 in the store) that you can carry around (and show off!). To be able to actually use the spec, the team at PublicLab built an open source software called Spectral Workbench that runs within your browser to help you record and analyze the data you collect.

Source: Plan for analyzing the environment

You’ll find pictures of the smartphone and other versions of do-it-yourself spectrometers at the publiclab.org website.

If you missed the video wherein the homemade spectrometer was constructed, you can see it here.

Sharing of data on the environment has been made possible through this online software developed by publiclab.org:

The Arduino with MQ gas sensor beats the GC-MS system for VOC detection.

The publiclab.org project has not provided a way to easily analyze indoor air, although it can analyze water and oil, among other things.

For this reason, the use of the Arduino board with MQ (Message Queueing) gas sensors, discussed on pages 17 and 18 of this article, remains an important affordable option for those with the time, interest, and skill to devote to it.

Humans breathe in VOCs and retain VOCs in their bloodstream (and mother’s milk) for hours after they leave the area containing the VOCs.  Sometimes they remain indoors for days, with continuous exposure. Remediation is possible without exact identification of the problem Volatile Organic Compound, but identification of the gas would seem to make remediation more likely. These exposures might be avoided if identified along with a path to remediation.

For those who find the Arduino solution of interest, a list of the MQ gas detectors, and the chemicals which they detect, is found here.

Click next page to see our conclusion and links to plant lists and the VOCs they can remove from the air.